Multiple electrode substrate support assembly and phase control system

ABSTRACT

Implementations described herein provide a substrate support assembly which enables tuning of a plasma within a plasma chamber. In one embodiment, a method for tuning a plasma in a chamber is provided. The method includes providing a first radio frequency power and a direct current power to a first electrode in a substrate support assembly, providing a second radio frequency power to a second electrode in the substrate support assembly at a different location than the first electrode, monitoring parameters of the first and second radio frequency power, and adjusting one or both of the first and second radio frequency power based on the monitored parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/742,142, filed Jun. 17, 2015, which application is incorporated byreference herein.

BACKGROUND Field

Embodiments disclosed herein generally relate to semiconductormanufacturing and more particularly to a substrate support assembly andmethod of using the same.

Description of the Related Art

As the feature size of the device patterns get smaller, the criticaldimension (CD) requirements of these features become a more importantcriterion for stable and repeatable device performance. Allowable CDvariation across a substrate processed within a processing chamber isdifficult to achieve due to chamber asymmetries such as chamber andsubstrate temperature, flow conductance, and RF fields.

In the current semiconductor manufacturing industry, transistorstructures have become increasingly complicated and challenging with thedevelopment of the FinFet technology, for example. On the substrateprocessing level, there is a need for advancements in process uniformitycontrol to allow fine, localized process tuning as well as globalprocessing tuning across the whole substrate. As the transistor densityacross a substrate increases according to the square of the radius,there is a demand for the capability to control the process at thesubstrate edge, where the electromagnetic field and plasma density andchemistry change due to the existence of multiple material interfacesand/or multiple geometric shapes.

Thus, there is a need for an improved substrate support assembly thatprovides aspects that improve process tuning.

SUMMARY

Implementations disclosed herein provide methods and apparatus whichenables tuning of a plasma within a plasma chamber. In one embodiment, amethod for tuning a plasma in a chamber is provided. The method includesproviding a first radio frequency power and a direct current power to afirst electrode adjacent to a substrate support surface of a substratesupport assembly, providing a second radio frequency power to a secondelectrode in the substrate support assembly at a location further fromthe support surface, monitoring parameters of the first and second radiofrequency power, and adjusting one or both of the first and second radiofrequency power based on the monitored parameters.

In another embodiment, a method for tuning a plasma in a chamber isprovided. The method includes providing a first radio frequency powerand a direct current power to a first electrode adjacent to a substratesupport surface of a substrate support assembly, providing a secondradio frequency power to a second electrode in the substrate supportassembly at a location further from the support surface, monitoringparameters of the first and second radio frequency power, and shifting aphase of one or both of the first and second radio frequency power basedon the monitored parameters.

In another embodiment, a substrate support assembly is provided. Thesubstrate support assembly includes a body having a chucking electrodeembedded therein, the chucking electrode including a first radiofrequency electrode disposed adjacent to a substrate support surface ofthe body. The body also includes a second radio frequency electrodedisposed in the substrate support assembly at a location further fromthe support surface. The substrate support assembly also includes apower application system coupled to the substrate support assembly. Thepower application system includes a radio frequency power source coupledto one or both of the first and second radio frequency electrodesthrough a matching network, and a sensor coupled between the matchingcircuit and the first and second radio frequency electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments disclosed herein, some of which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical implementations of this disclosure andare therefore not to be considered limiting of its scope, for thedisclosure may admit to other equally effective implementations.

FIG. 1 is a cross-sectional schematic view of an exemplary etchprocessing chamber having one embodiment of a substrate supportassembly.

FIG. 2 is a partial schematic cross-sectional view of another embodimentof a processing chamber with another embodiment of a substrate supportassembly and a power application system.

FIG. 3 is a partial schematic cross-sectional view of another embodimentof a processing chamber with another embodiment of a substrate supportassembly and a power application system.

FIG. 4 is an exemplary phase diagram showing a first waveform and asecond waveform according to one embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneimplementation may be beneficially used in other implementations withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments disclosed herein provide a substrate support assembly and apower application system which enables tuning of a plasma in aprocessing chamber. The substrate support assembly may include multipleelectrodes which are coupled to a power application system enables phasecontrol of the plasma in the chamber. The phase control may be used tomanipulate plasma uniformity and/or plasma distribution within thechamber. The controlled plasma distribution may be utilized to tuneplasma density radially across a substrate. For example, the plasma maybe tuned to have a profile with a greater density at the edge of thesubstrate relative a density at the center of the substrate, and viceversa. Although the substrate support assembly and power applicationsystem is described below in an etch processing chamber, the substratesupport assembly and power application system may be utilized in othertypes of plasma processing chambers, such as physical vapor depositionchambers, chemical vapor deposition chambers, ion implantation chambers,stripping chambers, among others, as well as other plasma systems wheretuning of a plasma profile is desirable.

FIG. 1 is a cross-sectional schematic view of an exemplary etchprocessing chamber 100 having a substrate support assembly 101. Asdiscussed above, the substrate support assembly 101 may be utilized inother processing chambers, for example plasma treatment chambers,chemical vapor deposition chambers, ion implantation chambers, strippingchambers, among others, as well as other systems where the ability tocontrol a plasma profile at a surface of a substrate, is desirable.

The processing chamber 100 includes a grounded chamber body 102. Thechamber body 102 includes walls 104, a bottom 106 and a lid 108 whichenclose an internal volume 124. The substrate support assembly 101 isdisposed in the internal volume 124 and supports a substrate 134 thereonduring processing. The walls 104 of the processing chamber 100 includean opening (not shown) through which the substrate 134 may berobotically transferred into and out of the internal volume 124. Apumping port 110 is formed in one of the walls 104 or the bottom 106 ofthe chamber body 102, and is fluidly connected to a pumping system (notshown). The pumping system is utilized to maintain a vacuum environmentwithin the internal volume 124 of the processing chamber 100, whileremoving processing byproducts.

A gas panel 112 provides process and/or other gases to the internalvolume 124 of the processing chamber 100 through one or more inlet ports114 formed through at least one of the lid 108 or walls 104 of thechamber body 102. The process gas provided by the gas panel 112 isenergized within the internal volume 124 to form a plasma 122. Theplasma 122 is utilized to process the substrate 134 disposed on thesubstrate support assembly 101. The process gases may be energized by RFpower inductively coupled to the process gases from a plasma applicator120 positioned outside the chamber body 102. In the exemplary embodimentdepicted in FIG. 1, the plasma applicator 120 is a pair of coaxial coilscoupled through a matching circuit 118 to an RF power source 116. Inother embodiments (not shown), the plasma applicator may be anelectrode, such as a showerhead, that may be used in a capacitivelycoupled plasma system. The plasma 122 may also be formed utilizing othertechniques.

The substrate support assembly 101 generally includes at least asubstrate support 132. The substrate support 132 may be a vacuum chuck,an electrostatic chuck, a susceptor, or other substrate support surface.In the embodiment of FIG. 1, the substrate support 132 is anelectrostatic chuck and will be described hereinafter as anelectrostatic chuck 126.

The substrate support assembly 101 may additionally include a heaterassembly 170. The substrate support assembly 101 may also include acooling base 130. The cooling base 130 may alternately be separate fromthe substrate support assembly 101. The substrate support assembly 101may be removably coupled to a support pedestal 125. The support pedestal125, which may include a pedestal base 128 and a facility plate 180, ismounted to the chamber body 102. The pedestal base 128 may comprise adielectric material that electrically insulates electrically conductiveportions of the substrate support assembly 101 from the chamber body102. The substrate support assembly 101 may be periodically removed fromthe support pedestal 125 to allow for refurbishment of one or morecomponents of the substrate support assembly 101.

The substrate support assembly 101 includes a chucking electrode 136,which may be a mesh of a conductive material. The electrostatic chuck126 has a mounting surface 131 and a substrate support surface 133opposite the mounting surface 131. The chucking electrode 136 is coupledto a chucking power source 138 that, when energized, electrostaticallyclamps the substrate 134 to the workpiece support surface 133. Theelectrostatic chuck 126 generally includes the chucking electrode 136embedded in a dielectric puck or body 150. The dielectric body 150, aswell as other portions of the substrate support assembly 101 and thesupport pedestal 125, may be disposed within an insulator ring 143. Theinsulator ring 143 may be a dielectric material, such as quartz or otherdielectric material that is process compatible. A focus ring 145 may bedisposed about a periphery of the dielectric body 150. The focus ring145 may be a dielectric or conductive material and may comprise the samematerial as the substrate 134. The focus ring 145 may be utilized toextend the surface of the substrate 134 with respect to theelectromagnetic field of the plasma 122. The focus ring 145 may alsominimize the enhancement of electromagnetic field at the edge of thesubstrate 134, as well as minimize the chemistry effects due to thechange in materials at this interface.

The chucking electrode 136 may be configured as a mono polar or bipolarelectrode, or have another suitable arrangement. The chucking electrode136 is coupled through an RF filter 182 to a chucking power source 138which provides direct current (DC) power to electrostatically secure thesubstrate 134 to the upper surface of the dielectric body 150. The RFfilter 182 prevents RF power utilized to form the plasma 122 within theprocessing chamber 100 from damaging electrical equipment or presentingan electrical hazard outside the chamber. The dielectric body 150 may befabricated from a ceramic material, such as AlN or Al₂O₃. Alternately,the dielectric body 150 may be fabricated from a polymer, such aspolyimide, polyetheretherketone, polyaryletherketone and the like.

The cooling base 130 is used to control the temperature of the substratesupport assembly 101. The cooling base 130 may be coupled to a heattransfer fluid source 144. The heat transfer fluid source 144 provides aheat transfer fluid, such as a liquid, gas or combination thereof, whichis circulated through one or more conduits 160 disposed in the coolingbase 130. The fluid flowing through neighboring conduits 160 may beisolated to enabling local control of the heat transfer between theelectrostatic chuck 126 and different regions of the cooling base 130,which assists in controlling the lateral temperature profile of thesubstrate 134. The substrate support assembly 101 may also include theheater assembly 170 that includes one or more resistive heaters (notshown) encapsulated therein. The heater assembly 170 is coupled to aheater power source 156 that may be used to control power to theresistive heaters. The heater power source 156 may be coupled through anRF filter 184. The RF filter 184 may be used to protect the heater powersource 156 from the RF energy. The electrostatic chuck 126 may includeone or more temperature sensors (not shown) for providing temperaturefeedback information to the controller 148 for controlling the powerapplied by the heater power source 156 and for controlling theoperations of the cooling base 130.

The substrate support surface 133 of the electrostatic chuck 126 mayinclude gas passages (not shown) for providing backside heat transfergas to the interstitial space defined between the substrate 134 and thesubstrate surface 133 of the electrostatic chuck 126. The electrostaticchuck 126 may also include lift pin holes for accommodating lift pins(both not shown) for elevating the substrate 134 above the substratesupport surface 133 of the electrostatic chuck 126 to facilitate robotictransfer into and out of the processing chamber 100.

A power application system 135 is coupled to the substrate supportassembly 101. The power application system 135 may include the chuckingpower source 138, a first radio frequency (RF) power source 142, and asecond RF power source 178. Embodiments of the power application system135 may additionally include a controller 148, and a sensor device 181that is in communication with the controller 148 and both of the firstRF power source 142 and the second RF power source 178.

The controller 148 may be one of any form of general-purpose dataprocessing system that can be used in an industrial setting forcontrolling the various subprocessors and subcontrollers. Generally, thecontroller 148 includes a central processing unit (CPU) 172 incommunication with memory 174 and input/output (I/O) circuitry 176,among other common components. Software commands executed by the CPU ofthe controller 148, cause the processing chamber to, for example,introduce an etchant gas mixture (i.e., processing gas) into theinternal volume 124. The controller 148 may also be utilized to controlthe plasma 122 from the processing gas by application of RF power fromthe plasma applicator 120, the first RF power source 142 and the secondRF power source 178 in order to etch a layer of material on thesubstrate 134.

As described above, the substrate support assembly 101 includes thechucking electrode 136 that may function in one aspect to chuck thesubstrate 134 while also functioning as a first RF electrode. The heaterassembly 170 may also include a second RF electrode 154, and togetherwith the chucking electrode 136, applies RE power to tune the plasma122. The first RF power source 142 may be coupled to the second RFelectrode 154 while the second RF power source 178 may be coupled to thechucking electrode 136. A first matching network 151 and a secondmatching network 152 may be provided for the first RF power source 142and the second RF power source 178, respectively. The second RFelectrode 154 may be a solid metal plate of a conductive material asshown. Alternatively, the second RF electrode 154 may be a mesh ofconductive material.

The first RF power source 142 and the second RF power source 178 mayproduce power at the same frequency or a different frequency. In someembodiments, one or both of the first RF power source 142 and the secondRF power source 178 may produce power at a frequency of 13.56 megahertz(MHz) or a frequency of 2 MHz. In other embodiments, the first RF powersource 142 may produce power at a frequency of 13.56 MHz and the secondRF power source 178 may produce power at a frequency of 2 MHz, or viceversa. RF power from one or both of the first RF power source 142 andsecond RF power source 178 may be varied in order to tune the plasma122. For example, the sensor device 181 may be used to monitor the RFenergy from one or both of the first RF power source 142 and the secondRF power source 178. Data from the sensor device 181 may be communicatedto the controller 148, and the controller 148 may be utilized to varypower applied by the first RF power source 142 and the second RF powersource 178. In one embodiment, phase angle of one or both of the firstRF power source 142 and the second RF power source 178 is monitored andadjusted in order to tune the plasma 122.

By changing the phase angle, the plasma uniformity can be tuned.Changing the phase angle will change the voltage/current distributionacross the chucking electrode 136 and the second RF electrode 154.Varying the phase angle may also tune the spatial distribution of theplasma across the substrate 134. For example, the phase angle can beutilized to fine tune the process, whether etch rate is center fast, oredge fast, or flat. Adjusting the phase angle may also impact on thesheath dynamics which directly affects processing results. As thechucking electrode 136 is closer to the plasma 122 and the surface ofthe substrate 134 as compared to the second RF electrode 154, control ofthe plasma according to this aspect may be extremely effective. In someembodiments, the power application system 135 provides three modes ofcontrol including controlling RF power (e.g., frequency and/or wattage)to the chucking electrode 136, controlling RF power (e.g., frequencyand/or wattage) to the second RF electrode 154, and control of the phasebetween the chucking electrode 136 and the second RF electrode 154. Thiscontrol scheme provides greater process tuning ability and/or thecapability for effective edge control. The increased edge control may bedue to the size difference of the two concentric electrodes and/or phasecontrol of the RF power applied thereto.

In some embodiments, the surface area of the second RF electrode 154 maybe greater than a surface area of the chucking electrode 136. Forexample, the chucking electrode 136 may include a first dimension ordiameter while the second RF electrode 154 has a second dimension ordiameter that is greater than the first diameter. In one embodiment, thechucking electrode 136 has a first diameter that is substantially equalto a diameter of the substrate 134. The second RF electrode 154 mayinclude a second diameter that is greater than the first diameter. Inone embodiment, the second RF electrode 154 may have a surface area thatis about 50% greater than a surface area of the chucking electrode 136.In other embodiments, the second RF electrode 154 may have a surfacearea that is about 70% to about 80% greater than a surface area of thechucking electrode 136. In one or more embodiments, the difference insurface area may be utilized to control the process rate at differentlocations of the substrate 134. For example, if power delivered to thesecond RF electrode 154 is increased, the processing rate of the edge ofthe substrate 134 increases. If power delivered to the chuckingelectrode 136 is increased, then the central area of the substrate 134may be etched at a faster rate with little impact on the edge of thesubstrate 134. Therefore, a differential control for discrete regions onthe entire substrate 134 is achieved.

FIG. 2 is a partial schematic cross-sectional view of another embodimentof a processing chamber 200 having a substrate support assembly 101 anda power application system 205. Only a lower portion of the processingchamber 200 is shown as the substrate support assembly 101 and the powerapplication system 205 may be utilized in many types of processingchambers. For example, the upper portion of the processing chamber 200may be configured with hardware for plasma etching, chemical vapordeposition, ion implantation, stripping, physical vapor deposition,plasma annealing, and plasma treatment, among others.

The processing chamber 200 includes the substrate support assembly 101having the second RF electrode 154 coupled to the first RF power source142 through matching network 151. The chucking electrode 136 is coupledto the second RF power source 178 through matching network 152. Thefirst RF power source 142, the first matching network 151 and the secondRF electrode 154 may comprise a first RF system 210 of the powerapplication system 205. Similarly, the second RF power source 178, thesecond matching network 152 and the chucking electrode 136 may comprisea second RF system 215 of the power application system 205.

The power application system 205 includes the sensor device 181 that inone embodiment includes a first sensor 220 and a second sensor 225. Eachof the first sensor 220 and the second sensor 225 may be voltage andcurrent sensors (e.g., V/I sensors). Thus, the voltage and current ofeach of the first RF system 210 and the second RF system 215 may bemonitored and tuned according to embodiments described herein. Signalsfrom each of the first sensor 220 and the second sensor 225 may betransmitted to the controller 148 and power applied to each of the firstRF system 210 and the second RF system 215 may be varied and tuned tocontrol distribution and/or density of plasma within the processingchamber 200.

FIG. 3 is a partial schematic cross-sectional view of another embodimentof a processing chamber 300 having a substrate support assembly 101 anda power application system 305. Only a lower portion of the processingchamber 300 is shown as the substrate support assembly 101 and the powerapplication system 305 may be utilized with other processing chambers.For example, the upper portion of the processing chamber 200 may beconfigured with hardware for plasma etching, chemical vapor deposition,ion implantation, stripping, physical vapor deposition, plasmaannealing, and plasma treatment, among others.

The processing chamber 300 includes the substrate support assembly 101having the chucking electrode 136 coupled to the first RF power source142. However, in this embodiment, a second RF electrode 310 is alsocoupled to the first RF power source 142. The second RF electrode 310may be disposed in a ceramic plate 315 positioned between the coolingbase 130 and the dielectric body 150 of the electrostatic chuck 126. Thesecond RF electrode 310 may be separated from the chucking electrode 136by a metallic ground plate 320. The metallic ground plate 320 may bepositioned between the ceramic plate 315 and the dielectric body 150.The metallic ground plate 320 is utilized to electromagnetically isolatethe second RF electrode 310 from the chucking electrode 136. The secondRF electrode 310 may be a conductive mesh 325. Alternatively, the secondRF electrode 310 may be a solid plate made of a conductive material. Themetallic ground plate 320 may be an aluminum plate that is coupled toground potential.

The first RF power source 142 is operably coupled to both of thechucking electrode 136 and the second RF electrode 310. A singlematching network 330 is disposed between the first RF power source 142and each of the chucking electrode 136 and the second RF electrode 310.Thus, a first RF system 335 and a second RF system 340 are provided, andthe chucking electrode 136 and the second RF electrode 310 of eachsystem share the first RF power source 142 and the matching network 330.The sensor device 181 includes the first sensor 220 and the secondsensor 225 as in other embodiments, but the sensor device 181 may beoptional or utilized only for initial and/or periodic calibration. Oneor both of a controller 345 and a phase shifter 350 may also be includedin each of the first RF system 335 and the second RF system 340. Forexample, the phase shifter 350 may be utilized to control phase anglebased on feedback from the sensor device 181, which may negate a needfor the controller 345 being utilized to control operation of the powerapplication system 305.

In some embodiments, the matching network 330 may be utilized as a powersplitter that varies power from the first RF power source 142 to each ofthe chucking electrode 136 and the second RF electrode 310. Utilizingone RF generator together with a power splitting circuit 360 and a phasecontrol/delay circuit (e.g., phase shifter 350) to implement multipleelectrode driving may reduce costs of ownership. In other embodiments,the circuit of matching network 330 serves two functions. A firstfunction may be impedance matching while the second function may bepower splitting between the chucking electrode 136 and the second RFelectrode 310. The manner of power splitting may be controllable througha variable impedance circuit 355 coupled to either the chuckingelectrode 136 or the second RF electrode 310. The variable impedancecircuit 355 may be utilized to vary the relative impedances the chuckingelectrode 136 and the second RF electrode 310. In some embodiments,varying the relative impedances the chucking electrode 136 and thesecond RF electrode 310 changes the power distribution between thechucking electrode 136 and the second RF electrode 310. Changing thepower distribution between the second RF electrode 310 and the chuckingelectrode 136 may be utilized to tune the plasma.

In some embodiments, the phases of the RF signals from the first RFpower source 142 after splitting and matching are sensed by the firstsensor 220 and the second sensor 225. The signals may be transmitted tothe controller 345. The controller 345 may be utilized to control thephase shifter 350 to control the phase difference between the chuckingelectrode 136 and the second RF electrode 310. The phase shifter 345 maybe a phase delay circuit or a more advanced device such as high RF powervector modulator. The two RF hot electrodes, the chucking electrode 136and the second RF electrode 310, are electrically separated from eachother in this embodiment. Decoupling of the chucking electrode 136 orthe second RF electrode 310 can produce easier phase and/or powercontrol since the crosstalk between multiple RF generators is decreased.Decoupling may also provide more sensitive and/or effective edge tuning.The improved edge tuning may be due to the relative sizes of the secondRF electrode 310 and the chucking electrode 136 as the larger electrodemay have a lesser impact on the center area of the substrate 134.Additionally, the decoupling may also increase the phase angle operatingregime. Further, if the whole system is fabricated according to the samestandard, the first sensor 220 and the second sensor 225 may not benecessary for the chamber after initial calibration.

FIG. 4 is an exemplary phase diagram 400 showing a first waveform 405and a second waveform 410. The first waveform 405 may be indicative ofthe RE signal from the first RF system 210 (FIG. 2) or 335 (FIG. 3), andthe second waveform 410 may be indicative of the RF signal from thesecond RF system 215 (FIG. 2) or 340 (FIG. 3). The first waveform 405and the second waveform 410 may be measured by the first sensor 220 andthe second sensor 225 (FIGS. 2 or 3) downstream of a matching network.While the first waveform 405 and the second waveform 410 are shown ashaving the same frequency and amplitude in this example, the firstwaveform 405 and the second waveform 410 may have a different frequencyand/or amplitude.

The phase difference θ between the first waveform 405 and the secondwaveform 410 may be varied as desired based on the desiredcharacteristics of a plasma. The phase angle may be varied between about0 degrees to about 360 degrees. The first waveform 405 and the secondwaveform 410 may be constructive or destructive based on the desiredcharacteristics of a plasma.

Control of the RF phase difference and/or phase angle provides apowerful knob for fine process tuning. For example, control of the RFphase difference and/or phase angle may be utilized to control one ormore of average etch rate, etch rate uniformity, etch rate skew,critical dimension (CD) uniformity, CD skew, CD range, and plasmauniformity and/or plasma density.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

We claim:
 1. A substrate support assembly, comprising: a body having achucking electrode embedded therein, the chucking electrode comprising afirst electrode disposed adjacent to a substrate support surface of thebody; a second electrode disposed in the substrate support assembly at alocation further from the support surface; and a power applicationsystem coupled to the substrate support assembly, wherein the powerapplication system comprises: a radio frequency power source coupled toone or both of the first and second electrodes through a matchingnetwork; and a sensor coupled between the matching circuit and the firstand second electrodes.
 2. The support assembly of claim 1, wherein thesecond electrode includes a surface area that is greater than a surfacearea of the first electrode.
 3. The support assembly of claim 1, whereinthe second electrode includes a diameter that is greater than a diameterof the first electrode.
 4. The support assembly of claim 1, wherein thepower application system includes a first radio frequency power sourcecoupled to the first electrode and a second radio frequency power sourcecoupled to the second electrode.
 5. The support assembly of claim 1,wherein the power application system comprises a single radio frequencypower source coupled to both of the first electrode and the secondelectrode.
 6. The support assembly of claim 5, further comprising apower splitter coupled between the radio frequency power source and bothof the first electrode and the second electrode.
 7. The support assemblyof claim 1, wherein the body comprises a dielectric material.
 8. Thesupport assembly of claim 1, wherein first electrode has a diameter thatis substantially equal to a diameter of a substrate.
 9. The supportassembly of claim 1, further comprising a phase shifter coupled to oneor both of the first electrode and the second electrode.
 10. A substratesupport assembly, comprising: a dielectric body having a chuckingelectrode embedded therein, the chucking electrode comprising a firstelectrode adapted to form a plasma that is positioned adjacent to asubstrate support surface of the body; a second electrode disposed inthe dielectric body at a location further from the support surface; anda power application system coupled to the substrate support assembly,wherein the power application system comprises: a radio frequency powersource coupled to one or both of the first and second electrodes througha matching network; and a sensor coupled between the matching circuitand the first and second electrodes.
 11. The support assembly of claim10, wherein the second electrode includes a surface area that is greaterthan a surface area of the first electrode.
 12. The support assembly ofclaim 10, wherein the second electrode includes a diameter that isgreater than a diameter of the first electrode.
 13. The support assemblyof claim 10, wherein the power application system includes a first radiofrequency power source coupled to the first electrode and a second radiofrequency power source coupled to the second electrode.
 14. The supportassembly of claim 10, wherein the power application system comprises asingle radio frequency power source coupled to both of the firstelectrode and the second electrode.
 15. The support assembly of claim14, further comprising a power splitter coupled between the radiofrequency power source and both of the first electrode and the secondelectrode.
 16. The support assembly of claim 10, wherein the bodycomprises a dielectric material.
 17. The support assembly of claim 10,wherein first electrode has a diameter that is substantially equal to adiameter of a substrate.
 18. The support assembly of claim 10, furthercomprising a phase shifter coupled to one or both of the first electrodeand the second electrode.
 19. A substrate support assembly, comprising:a dielectric body having a chucking electrode embedded therein, thechucking electrode comprising a first electrode adapted to form a plasmathat is positioned adjacent to a substrate support surface of the body,wherein first electrode has a diameter that is substantially equal to adiameter of a substrate; a second electrode embedded in the dielectricbody at a location further from the support surface, wherein the secondelectrode includes a surface area that is greater than a surface area ofthe first electrode; and a power application system coupled to thesubstrate support assembly, wherein the power application systemcomprises: a radio frequency power source coupled to one or both of thefirst and second electrodes through a matching network; and a sensorcoupled between the matching circuit and the first and secondelectrodes.
 20. The support assembly of claim 19, wherein the powerapplication system comprises a single radio frequency power sourcecoupled to both of the first electrode and the second electrode.